Cortisol is the major glucocorticoid hormone synthesised from cholesterol in the adrenal cortex. Synthesis is stimulated by the anterior pituitary adrenocorticotrophic hormone (ACTH), which is under control of the hypothalamic peptide, corticotrophin-releasing hormone (CRH).
As cortisol concentrations increase, the binding capacity of cortisol binding globulin in the circulation is exceeded, resulting in a disproportionate rise in urine cortisol concentrations. Urine cortisol measurement is useful as a screening test for cortisol excess (Cushing’s syndrome). Urine cortisol measurement can also be used as part of a dexamethasone suppression test. Multiple EMU cortisol measurements may also be useful in the investigation of possible cyclical Cushing's.
Sample Requirements and Reference Ranges
|Sample type||Urine (24 hr, random or early morning urine)|
|Container||Plain urine container (no preservative)|
|Minimum volume||10 mL|
|Reference range|| Adults (EMU): <40 nmol/mmol creatinine
Adults (24 hour): <165 nmol/24 hourChildren (≤10 yrs): <40 nmol/mmol creatinine
|Turnaround time||14 days|
|Method||Liquid chromatography-tandem mass spectrometry|